package com.java.demo;

import javax.crypto.Cipher;
import java.lang.reflect.Method;
import java.security.*;
import java.security.spec.PKCS8EncodedKeySpec;
import java.security.spec.X509EncodedKeySpec;
import java.util.Base64;
import java.util.HashMap;
import java.util.Map;

/**
 * @Description:
 * @Auther: sixbing  QQ:414409451
 * @Date: 2018/12/10 15:40
 */
public class RSAUtils {
    public static final String KEY_ALGORITHM = "RSA";
    public static final String SIGNATURE_ALGORITHM = "MD5withRSA";

    private static final String PUBLIC_KEY = "RSAPublicKey";
    private static final String PRIVATE_KEY = "RSAPrivateKey";

    public static byte[] decryptBASE64(String key) throws Exception {
        return decodeBase64(key);
    }

    public static String encryptBASE64(byte[] bytes) throws Exception {
        return encodeBase64(bytes);
    }

    /**
     * 用私钥对信息生成数字签名
     *
     * @param data       加密数据
     * @param privateKey 私钥
     * @return
     * @throws Exception
     */
    public static String sign(byte[] data, String privateKey) throws Exception {
        // 解密由base64编码的私钥
        byte[] keyBytes = decryptBASE64(privateKey);
        // 构造PKCS8EncodedKeySpec对象
        PKCS8EncodedKeySpec pkcs8KeySpec = new PKCS8EncodedKeySpec(keyBytes);
        // KEY_ALGORITHM 指定的加密算法
        KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
        // 取私钥匙对象
        PrivateKey priKey = keyFactory.generatePrivate(pkcs8KeySpec);
        // 用私钥对信息生成数字签名
        Signature signature = Signature.getInstance(SIGNATURE_ALGORITHM);
        signature.initSign(priKey);
        signature.update(data);
        return encryptBASE64(signature.sign());
    }

    /**
     * 校验数字签名
     *
     * @param data      加密数据
     * @param publicKey 公钥
     * @param sign      数字签名
     * @return 校验成功返回true 失败返回false
     * @throws Exception
     */
    public static boolean verify(byte[] data, String publicKey, String sign)
            throws Exception {
        // 解密由base64编码的公钥
        byte[] keyBytes = decryptBASE64(publicKey);
        // 构造X509EncodedKeySpec对象
        X509EncodedKeySpec keySpec = new X509EncodedKeySpec(keyBytes);
        // KEY_ALGORITHM 指定的加密算法
        KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
        // 取公钥匙对象
        PublicKey pubKey = keyFactory.generatePublic(keySpec);
        Signature signature = Signature.getInstance(SIGNATURE_ALGORITHM);
        signature.initVerify(pubKey);
        signature.update(data);
        // 验证签名是否正常
        return signature.verify(decryptBASE64(sign));
    }

    public static byte[] decryptByPrivateKey(byte[] data, String key) throws Exception {
        // 对密钥解密
        byte[] keyBytes = decryptBASE64(key);
        // 取得私钥
        PKCS8EncodedKeySpec pkcs8KeySpec = new PKCS8EncodedKeySpec(keyBytes);
        KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
        Key privateKey = keyFactory.generatePrivate(pkcs8KeySpec);
        // 对数据解密
        Cipher cipher = Cipher.getInstance(keyFactory.getAlgorithm());
        cipher.init(Cipher.DECRYPT_MODE, privateKey);
        return cipher.doFinal(data);
    }

    /**
     * 解密<br>
     * 用私钥解密
     *
     * @param data
     * @param key
     * @return
     * @throws Exception
     */
    public static byte[] decryptByPrivateKey(String data, String key)
            throws Exception {
        return decryptByPrivateKey(decryptBASE64(data), key);
    }

    /**
     * 解密<br>
     * 用公钥解密
     *
     * @param data
     * @param key
     * @return
     * @throws Exception
     */
    public static byte[] decryptByPublicKey(byte[] data, String key)
            throws Exception {
        // 对密钥解密
        byte[] keyBytes = decryptBASE64(key);
        // 取得公钥
        X509EncodedKeySpec x509KeySpec = new X509EncodedKeySpec(keyBytes);
        KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
        Key publicKey = keyFactory.generatePublic(x509KeySpec);
        // 对数据解密
        Cipher cipher = Cipher.getInstance(keyFactory.getAlgorithm());
        cipher.init(Cipher.DECRYPT_MODE, publicKey);
        return cipher.doFinal(data);
    }

    /**
     * 加密<br>
     * 用公钥加密
     *
     * @param data
     * @param key
     * @return
     * @throws Exception
     */
    public static byte[] encryptByPublicKey(String data, String key)
            throws Exception {
        // 对公钥解密
        byte[] keyBytes = decryptBASE64(key);
        // 取得公钥
        X509EncodedKeySpec x509KeySpec = new X509EncodedKeySpec(keyBytes);
        KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
        Key publicKey = keyFactory.generatePublic(x509KeySpec);
        // 对数据加密
        Cipher cipher = Cipher.getInstance(keyFactory.getAlgorithm());
        cipher.init(Cipher.ENCRYPT_MODE, publicKey);
        return cipher.doFinal(data.getBytes());
    }

    /**
     * 加密<br>
     * 用私钥加密
     *
     * @param data
     * @param key
     * @return
     * @throws Exception
     */
    public static byte[] encryptByPrivateKey(byte[] data, String key)
            throws Exception {
        // 对密钥解密
        byte[] keyBytes = decryptBASE64(key);
        // 取得私钥
        PKCS8EncodedKeySpec pkcs8KeySpec = new PKCS8EncodedKeySpec(keyBytes);
        KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
        Key privateKey = keyFactory.generatePrivate(pkcs8KeySpec);
        // 对数据加密
        Cipher cipher = Cipher.getInstance(keyFactory.getAlgorithm());
        cipher.init(Cipher.ENCRYPT_MODE, privateKey);
        return cipher.doFinal(data);
    }

    /**
     * 取得私钥
     *
     * @param keyMap
     * @return
     * @throws Exception
     */
    public static String getPrivateKey(Map<String, Key> keyMap)
            throws Exception {
        Key key = (Key) keyMap.get(PRIVATE_KEY);
        return encryptBASE64(key.getEncoded());
    }

    /**
     * 取得公钥
     *
     * @param keyMap
     * @return
     * @throws Exception
     */
    public static String getPublicKey(Map<String, Key> keyMap)
            throws Exception {
        Key key = keyMap.get(PUBLIC_KEY);
        return encryptBASE64(key.getEncoded());
    }

    /**
     * 初始化密钥
     *
     * @return
     * @throws Exception
     */
    public static Map<String, Key> initKey() throws Exception {
        KeyPairGenerator keyPairGen = KeyPairGenerator
                .getInstance(KEY_ALGORITHM);
        keyPairGen.initialize(1024);
        KeyPair keyPair = keyPairGen.generateKeyPair();
        Map<String, Key> keyMap = new HashMap(2);
        keyMap.put(PUBLIC_KEY, keyPair.getPublic());// 公钥
        keyMap.put(PRIVATE_KEY, keyPair.getPrivate());// 私钥
        return keyMap;
    }

    /**
     * 编码
     *
     * @param input
     * @return
     * @throws Exception
     */
    public static String encodeBase64(byte[] input) throws Exception {
        Class clazz = Class.forName("com.sun.org.apache.xerces.internal.impl.dv.util.Base64");
        Method mainMethod = clazz.getMethod("encode", byte[].class);
        mainMethod.setAccessible(true);
        Object retObj = mainMethod.invoke(null, new Object[]{input});
        return (String) retObj;
    }

    /**
     * 解码
     *
     * @param input
     * @return
     * @throws Exception
     */
    public static byte[] decodeBase64(String input) throws Exception {
        Class clazz = Class.forName("com.sun.org.apache.xerces.internal.impl.dv.util.Base64");
        Method mainMethod = clazz.getMethod("decode", String.class);
        mainMethod.setAccessible(true);
        Object retObj = mainMethod.invoke(null, input);
        return (byte[]) retObj;
    }

    public static void main(String[] args) throws Exception {
        String privateKeyWord = "12345大萨达撒多6";
        String publicKeyWord = "123456";
        Map<String, Key> keyMap = initKey();
        String publicKey = "MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQDFtzz4Nmv7Fw/et19INRqSHyhjUC2E3PQTzHTUWa91HBJNbrwhUGBfJeImEQAUkg5LpmH3NcyPsvZfI7kqn0B6TBxOhE19aeQNvbba7hjAKFpGUX2MUWS7DssWUrZqCcwoGH235nFttyEErBROyzfLW4xpRN2P6nTMUkt2/y1c8QIDAQAB";
//          String publicKey = getPublicKey(keyMap);
        String privateKey = "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";
//        String privateKey = getPrivateKey(keyMap);
        System.out.println("keyMap:\n" + keyMap);

        System.out.println("\n**************************************************************************************************************\n");

        System.out.println("公钥：" + publicKey);
        System.out.println("");
        byte[] encryptByPublicKey = encryptByPublicKey(publicKeyWord, publicKey);
        System.out.println("公钥加密后:" + new String(encryptByPublicKey));
        System.out.println("");
        byte[] decryptByPrivateKey = decryptByPrivateKey(encryptByPublicKey, privateKey);
        System.out.println("私钥解密后:" + new String(decryptByPrivateKey));
        System.out.println("");

        System.out.println("\n**************************************************************************************************************\n");

        System.out.println("私钥：" + privateKey);
        System.out.println("");
        byte[] encryptByPrivateKey = encryptByPrivateKey(privateKeyWord.getBytes(), privateKey);
        System.out.println("私钥加密后:" + new String(encryptByPrivateKey));
        System.out.println("");
        byte[] decryptByPublicKey = decryptByPublicKey(encryptByPrivateKey, publicKey);
        System.out.println("公钥解密后:" + new String(decryptByPublicKey));
        System.out.println("");

        System.out.println("\n**************************************************************************************************************\n");

        String sign = sign(encryptByPrivateKey, privateKey);
        System.out.println("对私钥进行数字签名:" + sign);
        System.out.println("");
        boolean verify = verify(encryptByPrivateKey, publicKey, sign);
        System.out.println("校验数字签名结果:" + verify);

    }
}
